JPH109808A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a large rotational angle reliably over a wide range by fixing a magnetic displacement body directly to a rotator being detected and detecting the displacement of the rotator from an output voltage corresponding to a flux density being applied to a reluctance element. SOLUTION: A rotator (displacement body) 27 having radius enlarging gradually in the direction of an arrow A rotates in the direction of the arrow A through rotation of a rotator 26 to be detected. A reluctance element 24 is applied with a field lower than the saturation from a magnet 25 and since the spatial distance between the magnet 25 and the magnetic rotator 27 is varied depending on the variation in the radius of the rotator 27 through rotation thereof, the flux density being applied to the reluctance element 24 from the magnet 25 is also varied. Consequently, the reluctance of the reluctance element 24 is varies depending on the variation in the flux density and the variation of reluctance is outputted in the form of a voltage. The voltage is amplified through a circuit board 23 and fed through the terminal 28 of a connector 21 to a computer where the rotational angle of the rotator 26 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for detecting, for example, a rotation angle of a handle.

[0002]

2. Description of the Related Art FIG. 8 is a side view of a conventional magnetic sensor. The magnetic sensor includes a sensor body 1 and the sensor body 1.
And a connector 2 connected to the connector. Sensor body 1
Are a case 3, a circuit board 4 housed in the case 3, and a magnetoresistive element 5 attached to the circuit board 4.
A rotating shaft 8 which penetrates the case 3 and is rotatably supported by a bearing 9; and a magnet 10 attached to the tip of the rotating shaft 8 and applying a magnetic field to the magnetoresistive element 5. . The connector 2 has a terminal 6 electrically connected to the circuit board 4 and a connector body 7 made of an insulating resin and having an end portion of the terminal 6 exposed and embedded.

In this magnetic sensor, a rotating shaft 8 is connected to a detecting rotator 11 which is an object to be detected at a rotational angle, and the rotating rotator 11 rotates the rotating shaft 8 by a predetermined angle, and a magnet 10 also rotates by a predetermined angle. Rotate an angle. The disk-shaped magnet 10 applies a saturation magnetic field to the magnetoresistive element 5,
Due to the rotation of the magnet 10, the angle of the saturation magnetic field applied to the magnetoresistive element 5 changes, and the change in the magnetic field angle is output as a change in voltage by the magnetoresistive element 5. Magnetic resistance element 5
The change in the voltage generated in the step (1) is electrically processed by the circuit board 4, and the electric signal is sent to a computer unit (not shown) via the terminal 6 of the connector 2 and the rotation angle of the detection rotator 11 Is detected.

[0004] Figure 9 Figure 10 shows the rotation angle theta ₁ and the magnetoresistive element of the magnet 10 5 showing the manner applied at saturation magnetic field angle theta ₂ to the magneto-resistive element 5 when the rotation angle theta ₁ of the magnet 10 FIG. 11 is a relationship diagram showing the relationship between the saturation magnetic field angle θ ₂ applied to the magnetic field and the rotation angle θ ₁ of the magnet 10 and the magnetoresistive element 5.
FIG. 3 is a relationship diagram showing a relationship with an output voltage of a magnet 1;
When the rotation angle θ _{1 of} 0 is zero, the saturation magnetic field angle θ ₂ applied to the magnetoresistive element 5 from FIG.
1 indicates that the output voltage of the magnetoresistive element 5 is (V ₁ + V ₂ ) / 2. The rotation angle θ ₁ of the magnet 10 is 9
At 0 °, the magnetic field angle θ ₂ applied to the magnetoresistive element 5 from FIG. 10 is 90 °, and from FIG.
Output voltage is (V ₁ + V ₂ ) / 2.

[0005]

In a conventional magnetic sensor, as can be seen from FIG. 11, the rotation angle θ ₁ is about −
When the angle is 60 °, the output value of the magnetoresistive element 5 is the lowest,
When the angle is 60 °, the output value of the magnetoresistive element 5 becomes maximum,
When the rotation angle θ ₁ is in the range of −45 ° to + 45 °, the relationship between the rotation angle θ ₁ and the output voltage of the magnetoresistive element 5 is linear. Although the rotation angle can be detected by the magnetoresistive element 5, there is a problem that the rotation detection angle range of the detection rotator 11 is small.

Further, in the conventional magnetic sensor, a rotating shaft 8 is interposed between the detecting rotator 11 and the magnet 10, and a bearing 9 is provided to prevent the eccentric rotation of the rotating shaft 8 with respect to the detecting rotator 11. Is mounted on the case 3, and when used for a long period of time, the bearing 9 is worn out, and there is a problem that the life of the magnetic sensor is short.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem. For example, it is possible to detect a rotation angle of an object to be detected with high reliability over a large rotation angle range and to use it for a long time. An object of the present invention is to obtain a magnetic sensor that can be used.

[0008]

A magnetic sensor according to the present invention includes a magnet, a magnetoresistive element for outputting a voltage corresponding to the density of a magnetic flux applied by the magnet, and an object to be detected whose displacement is to be detected. And a displacement body made of a magnetic material that changes the density of a magnetic flux applied to the magnetoresistive element by a change in a spatial distance between the magnet and the magnet connected to the displacement.

Further, the magnet, the magnetoresistive element and the displacement body are arranged on the same straight line.

The displacement body is a rotating body that rotates and displaces, and the relationship between the rotation angle of the rotation body and the voltage value of the magnetoresistive element output corresponding to the rotation angle has a linear relationship. It has a shape having a curved surface portion.

The displacement body is a moving body that is linearly displaced, and has a slope portion such that the relationship between the linear movement amount of the moving body and the spatial distance between the moving body and the magnet is linear. It is a shape.

The displacement body is directly attached to the object to be detected.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a sectional view of a magnetic sensor showing an embodiment of the present invention, and FIG. 2 is a plan view of a main part of FIG. 1. The magnetic sensor comprises a sensor main body 20 and a connector connected to the sensor main body 20. 21. Sensor body 2
0 denotes a case 22, a circuit board 23 housed in the case 22, a magnetoresistive element 24 attached to the circuit board 23, and a magnetic field less than the saturation magnetic field applied to the magnetoresistive element 24 attached to the circuit board 23. A magnet 25 for applying
A rotating body 27, which is a displacement body made of a ferromagnetic material, which is directly attached to a tip end of a detecting rotating body 26 which is a body to be rotated. The rotating body 27 has a curved surface portion 27a whose radius gradually increases in the direction of arrow A as can be seen from FIG. Further, the magnet 25, the magnetoresistive element 24 and the rotating body 27 are arranged on the same straight line. The connector 21 has a terminal 28 electrically connected to the circuit board 23, and a connector main body 29 made of an insulating resin and having the end of the terminal 28 exposed and embedded.

In this magnetic sensor, the rotating body 27 is linearly mounted on the detecting rotating body 26, and the rotating rotating body 26 rotates in the direction of arrow A in FIG. On the other hand, although a magnetic field equal to or less than the saturation magnetic field is applied to the magnetoresistive element 24 from the magnet 25, the spatial distance between the magnet 25 and the rotating body 27 that is a magnetic body changes due to the rotation of the rotating body 27, As a result, the magnet 25 applied to the magnetoresistive element 24
The magnetic flux density changes from The resistance of the magnetoresistive element 24 changes in accordance with the change in the magnetic flux density, and the change in resistance is output as a voltage. The voltage output from the magnetoresistive element 24 is amplified by the circuit board 23, and the electric signal is sent to a computer unit (not shown) via the terminal 28 of the connector 21. An angle is detected.

In this embodiment, the rotating body 27 has a curved surface 27a so that the relationship as shown in FIG. 3, that is, the relationship between the rotation angle of the rotating body 27 and the output voltage of the magnetoresistive element 24 is linear. It has a shape having. This rotating body 27
Is determined by the following procedure. FIG. 4 shows the distance L between the rotating body and the magnet when the rotating body, the magnetoresistive element and the magnet are arranged on the same line, and the output of the magnetoresistive element arranged between the rotating body and the magnet. FIG. 4 shows that the value of the output voltage from the magnetoresistive element increases as the spatial distance L increases, that is, as the rotating body moves away from the magnet. From FIG. 4, the use output range of the magneto-resistive element is set, and the rotating body and the magnet corresponding to the output voltages V ₀ , V ₁ , V ₂ , V ₃ ‥‥ V _n of the respective magneto-resistive elements within the range are set. Distance between X ₀ , X ₁ , X ₂ , X ₃ ‥‥ X _n
Get. Next, the output voltages V ₀ , V ₁ , V ₂ , and V ₃ ‥‥ V of each magneto-resistive element are set so that the relation between the rotation angle of the rotating body and the output of the magneto-resistive element has a linear relationship shown in FIG. rotation angle theta ₁ of the rotating body that corresponds to _n, θ _2, obtaining the θ ₃ ‥‥ θ _n. Thereafter, as shown in FIG. 5, the radius R ₀ (Y−X ₀ ) of the rotating body at the rotation angle θ ₀ is obtained. Note that Y is the distance between the center of the rotating body and the side surface of the magnet. Similarly, the rotation angle theta ₁ with the rotating body radius _{R 1 (Y-X 1)} , the radius R ₂ of the rotating body at a rotational angle _{θ 2 (Y-X 2)} , rotating body ‥‥‥ rotation angle theta _n Is obtained as the radius R _n (Y−X _n ). Then, by connecting the respective ends of the radii R ₀ , R ₁ , R ₂ , and R ₃ ‥‥‥‥ R _n of the rotator, the rotator 27 having the smooth curved surface 27a shown in FIG. 5 is obtained. Can be

FIG. 6 is a diagram showing the relationship between the rotation angle of the rotating body 27 and the output voltage of the magnetoresistive element 24.
In this embodiment, the rotation angle of the rotating body 27 is approximately 0 ° to 2 °.
The relationship between the rotation angle of the rotator 27 and the output voltage of the magnetoresistive element 24 is linear in a large range of 70 °, and it is possible to detect the rotation angle of the detection rotator 26 with high reliability in this large range. it can.

In the prior art, the bearing 9 is mounted on the case 3 in order to prevent the eccentric rotation of the rotating shaft 8 with respect to the detecting rotator 11, and the wear of the bearing 9 adversely affects the life of the magnetic sensor. However, in this embodiment, the rotating body 27 is directly attached to the detecting rotating body 26, and the rotating shaft 8 that requires the bearing 9 is eliminated, so that the conventionally required bearing becomes unnecessary.
The wear of the bearing does not shorten the life of the magnetic sensor.

Embodiment 2 FIG. FIG. 7 is a sectional view of a magnetic sensor showing another embodiment of the present invention. In this embodiment, the detection moving body 31 is used to detect the amount of movement of the detection moving body 31 which is a linearly displaced detection object. The second embodiment differs from the first embodiment only in that a moving body 32 is attached to the first embodiment, and the other configuration is the same as that of the first embodiment.

The moving body 32 is made of a ferromagnetic material and has a flat plate shape having an inclined surface 32a at an end. The slope portion 32a is configured such that the relationship between the linear movement amount of the moving body 32 and the spatial distance M between the moving body 32 and the magnet 25 is linear, and moves in the direction of arrow B. When the body 32 is displaced linearly, the spatial distance M between the magnet 25 and the moving body 32 decreases, and as a result, the magnetic flux density applied from the magnet 25 to the magnetoresistive element 24 changes. The resistance of the magnetoresistive element 24 changes in accordance with the change in the magnetic flux density, and the change in resistance is output as a voltage. The voltage output from the magnetoresistive element 24 is
After that, this electric signal is sent to a computer unit (not shown) via the terminal 28 of the connector 21, and the linear movement amount of the detection moving body 31 is detected. In addition,
The smaller the inclination angle θ of the slope 32a is, the larger the amount of movement of the detection moving body 31 can be detected.

[0020]

As described above, according to the magnetic sensor of the present invention, the displacement of the object is detected from the voltage output according to the density of the magnetic flux applied to the magnetoresistive element. For example, when detecting a rotational displacement, compared with a conventional example in which the rotation angle of a detection object is detected from a voltage output according to the angle of a saturation magnetic field applied to the magnetoresistive element, The rotation angle range that can be detected is expanded.

Further, when the magnet, the magnetoresistive element and the displacement element are arranged on the same straight line, the angle of the magnetic field applied to the magnetoresistive element becomes constant, and the displacement amount of the object to be detected with high reliability can be detected. Can be.

When a rotating body having a curved surface portion is used as the displacement body such that the relationship between the rotation angle and the voltage value of the magnetoresistive element output corresponding to the rotation angle is linear. Thus, a highly reliable rotation angle of the object can be obtained.

When a moving body having a slope such that the relationship between the amount of linear movement and the spatial distance between the moving body and the magnet has a linear relationship is used as the displacement body, for example, the slope By reducing the inclination angle of the object, the range of the amount of movement of the object to be detected can be increased.

When the displacement body is directly attached to the object to be detected, the conventionally required bearing is not required, and the wear of the bearing does not shorten the life of the magnetic sensor.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic sensor according to an embodiment of the present invention.

FIG. 2 is a plan view of a main part of FIG.

FIG. 3 is a relationship diagram between a rotation angle of a displacement body and an output of a magnetoresistive element.

FIG. 4 shows a distance L between the displacement body and the magnet when the displacement body, the magnetoresistive element, and the magnet are arranged on the same line;
It is a relation diagram with the output of a magnetoresistive element.

FIG. 5 is an explanatory diagram for obtaining a shape of a displacement body.

FIG. 6 is a diagram showing a relationship between a rotation angle of the displacement body of FIG. 1 and an output of a magnetoresistive element.

FIG. 7 is a cross-sectional view of a magnetic sensor showing another embodiment of the present invention.

FIG. 8 is a sectional view of a conventional magnetic sensor.

9 is a diagram showing a state applied to the magnetoresistance element when the magnet of the rotational angle theta ₁ with the magnetic field angle theta _2.

FIG. 10 is a relationship diagram showing a relationship between a rotation angle θ _{1 of a} magnet and a magnetic field angle θ ₂ applied to a magnetoresistive element.

FIG. 11 is a relationship diagram showing a relationship between a rotation angle θ _{1 of a} magnet and an output voltage of a magnetoresistive element.

[Explanation of symbols]

Reference Signs List 20 sensor body, 23 circuit board, 24 magnetoresistive element, 25 magnet, 26 detecting rotating body, 27 rotating body (displacement body), 27a curved surface portion, 32 moving body (displacement body), 32
a Slope.

Continued on the front page (72) Inventor Wataru Fukui 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Yutaka Ohashi 2-3-2 Marunouchi 2-chome, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. In company

Claims (5)

[Claims] A magnet, a magnetoresistive element for outputting a voltage corresponding to the density of a magnetic flux applied by the magnet, and a magnet connected to an object to be detected whose displacement is to be detected and associated with the displacement. And a displacement body made of a magnetic material that changes the density of the magnetic flux applied to the magnetoresistive element according to a change in a spatial distance between the magnetic sensors. 2. The magnetic sensor according to claim 1, wherein the magnet, the magnetoresistive element, and the displacement body are disposed on the same straight line. 3. The displacement body is a rotating body that is rotationally displaced,
3. A shape having a curved surface portion such that a relationship between a rotation angle of the rotating body and a voltage value of the magnetoresistive element output corresponding to the rotation angle has a linear relationship. Magnetic sensor. 4. The displacement body is a moving body that linearly displaces,
The magnetic sensor according to claim 1 or 2, wherein the magnetic sensor has a slope having a linear relationship between a linear movement amount of the movable body and a spatial distance between the movable body and the magnet. 5. The magnetic sensor according to claim 1, wherein the displacement body is directly attached to the detection target.